diff --git a/pkgs/applications/video/k9copy/default.nix b/pkgs/applications/video/k9copy/default.nix
index 1e8883eae7ffa..02a0f275f570e 100644
--- a/pkgs/applications/video/k9copy/default.nix
+++ b/pkgs/applications/video/k9copy/default.nix
@@ -56,5 +56,8 @@ stdenv.mkDerivation rec {
     license = stdenv.lib.licenses.gpl2;
     maintainers = with stdenv.lib.maintainers; [ flosse ];
     platforms = stdenv.lib.platforms.unix;
+    # TODO: The software is deprecated and the build is broken, see:
+    # https://github.com/NixOS/nixpkgs/pull/63260#issuecomment-503506487
+    broken = true;
   };
 }
diff --git a/pkgs/development/libraries/kpmcore/default.nix b/pkgs/development/libraries/kpmcore/default.nix
index 5c53f5e6ad5da..52e6264843bfb 100644
--- a/pkgs/development/libraries/kpmcore/default.nix
+++ b/pkgs/development/libraries/kpmcore/default.nix
@@ -28,6 +28,8 @@ in stdenv.mkDerivation rec {
   enableParallelBuilding = true;
 
   meta = with stdenv.lib; {
-   maintainers = with lib.maintainers; [ peterhoeg ];
+    maintainers = with lib.maintainers; [ peterhoeg ];
+    # The build requires at least Qt 5.12:
+    broken = lib.versionOlder qtbase.version "5.12.0";
   };
 }